docs: 2026-10-14 session-death incident, guards, resolution findings

Document the new exit codes (76/77), the wrapper/unit fix, recovery steps, the
verbose output, and the archive-resolution check (images match a logged-in
fetch; 1080p VP9 exists for newer videos; iOS plays VP9+Opus webm but not
VP9+AAC mp4). Correct the stale "timers are disabled" line, and flag that the
repo's weekly profiles timer was never installed on the host.

TOOLING.md

@@ -23,9 +23,10 @@
 
 ## Quick reference — getting new content onto the site
 
-Timers are **disabled**, so this is manual today. Everything runs on
-`mattellite`; it fetches, publishes to the NAS itself, and the site picks it up
-with no deploy or restart.
+The three systemd timers (see "Scheduling" below) run these unattended; run
+them by hand only to get content sooner. Everything runs on `mattellite`; it
+fetches, publishes to the NAS itself, and the site picks it up with no deploy
+or restart.
 
 ```sh
 ssh mattellite
@@ -67,6 +68,74 @@ Long runs: `setsid nohup ~/gdl/run-profiles.sh >/dev/null 2>&1 &` (or `run-full-
 Nothing reaches the archive until a run finishes, so killing one midway is
 safe.
 
+## 2026-10-14 — the Instagram session died unnoticed; guards added
+
+**What happened.** Between 2026-10-06 09:12 and 2026-10-07 04:36 the dedicated
+Chrome's Instagram session died. Nothing alerted: the 10-07 full sweep logged
+`HTTP redirect to login page` on 17 of 18 sources (and "failed"), but every
+*stories* run after it fetched "No results" for all six profiles and still
+exited 0 — about a week of stories, which cannot be backfilled, was lost.
+Two compounding causes:
+
+- **No scheduled run had ever pinged Healthchecks.** `gdl-sync@.service` ran
+  `gdl-cron.sh %i` directly (written 08-20), but `HC_URL` is exported by the
+  `run-*.sh` wrappers (added 09-14), which the unit bypassed. `gdl-cron.sh`
+  skips the ping silently when `HC_URL` is empty. Fixed: the unit now runs
+  `run-%i.sh`. (`run-full-sweep.sh` has no check URL, so that mode still
+  does not ping.)
+- **An open Chrome tab keeps showing its logged-in UI after the session is
+  dead** — the SPA only notices on its next failed request. Looking at the
+  window proves nothing; **reload the tab, or read the cookie DB.** The cookie
+  jar had `csrftoken`, `ds_user_id`, `mid`… but no `sessionid`.
+
+**Guards now in `gdl-cron.sh`** (tests: `scripts/test_session_guards.py`):
+
+| exit | from | meaning |
+|---|---|---|
+| 76 | `check-session.py`, *before any request* | no unexpired `sessionid` in the Chrome profile gdl reads. The run aborts, logs why, pings `/76` (red check). Same DB, same profile as gdl, so it sees exactly what gdl would. Prints a `WARNING` (log only, no alert) when under 7 days of session remain |
+| 77 | `stories-streak.py`, *after a stories run* | every fetched stories source returned "No results" on 3 consecutive days (`GDL_EMPTY_STREAK_FAIL` to change). Catches a session Instagram stopped honouring while the cookie is still present, which the preflight cannot see. One day per calendar date, so manual re-runs do not inflate it; state in `~/gdl/stories-empty-streak` |
+| 75 | existing | every stories source skipped by `--min-interval` |
+
+**To recover from exit 76** the user must log in to Instagram in the Chrome on
+`mattellite` (VNC, display `:1`; neither password nor 2FA is something to
+script). Then `~/gdl/check-session.py` should say `session ok ... expires
+<date>`, and a manual `~/gdl/run-stories.sh` should find stories again.
+
+**Verbose output.** A healthy run looked hung: pacing is 12–20 s, the config
+sets `output: null` (no per-file lines), and the live-listing probe captured
+output until it finished. `gdl-sync.py` now prints `[n/N] user / kind (time)`,
+a `... fetching: 4m00s elapsed, 12 new file(s) so far (latest: …)` heartbeat
+every 60 s, and `done in 6m12s, 14 new file(s)`. It only counts files already
+written; no extra requests, pacing unchanged.
+
+**Archive resolution check** (read-only scan of header dimensions for the six
+scraped profiles, plus 8 single-post live metadata fetches, paced):
+
+- *Logged-out gdl does not download smaller files — it fails* with a login
+  redirect, so no logged-out media ever entered the archive.
+- Archived image sizes **match** what a logged-in fetch offers (1440×1800,
+  3277×4096, 2976×3720, and the genuinely small ones such as 400×400 or
+  742×928 sitting next to 1440 px siblings in one carousel). No image-upgrade
+  pass is needed.
+- Videos: ~1,200 of ~1,300 archived videos are 720p. A 2026 reel offers a
+  1080×1920 VP9 stream (video-only DASH, plus separate AAC); a 2024 post tops
+  out at 1276×720, same as the archive. A video upgrade would mostly benefit
+  2025–26 posts (~700), at one request each.
+- **iOS 18.7 Safari plays VP9 + Opus `.webm` but not VP9 + AAC `.mp4`** (error
+  code 4; `canPlayType` wrongly says "probably"). A video upgrade must
+  therefore output `.webm` — video stream copied, audio re-encoded to Opus
+  96k. **Not built yet.** Open points before building: the viewer mints every
+  video blob as `video/mp4` (`src/lib/archive-cache.ts`,
+  `src/hooks/useArchiveScanner.ts`) and must derive the MIME type from the
+  extension; superseded 720p files should be kept for review in a directory
+  *outside* the Resilio-synced, viewer-scanned `archives/` tree; and the
+  request budget (suggested: ≤40 posts/day, behind the preflight).
+
+**Open: profiles cadence.** `scripts/systemd/gdl-sync@profiles.timer` says
+weekly with a randomised day (commit 09-14) but the host is still on the
+monthly (3rd, 04:00) unit installed 08-22. The repo version was never
+installed; decide which one is wanted.
+
 ## 2026-09-14 — a tracked account renamed on Instagram: 0ct0ber19 → heejin
 
 HeeJin's handle changed and the old one is now fully dead — `instagram.com/
@@ -173,6 +242,13 @@ above, so a fully-skipped stories run alerts, not silently passes.
 Unset `HC_URL` (e.g. `HC_URL= ./run-stories.sh`) to run without pinging.
 `run-full-sweep.sh` and the reels scripts have no check configured yet.
 
+**The systemd unit must run the wrappers, not `gdl-cron.sh` directly** —
+`HC_URL` lives in `run-<mode>.sh`, and `gdl-cron.sh` skips the ping silently
+when it is empty. Until 2026-10-14 the unit bypassed the wrappers, so no
+scheduled run had ever pinged. The preflight (exit 76) and the all-empty
+streak (exit 77) are described in "2026-10-14" above; both reach the dashboard
+as failures through the same trailing-status-code convention.
+
 **This is also why `gdl-sync.py`'s `publish()` no longer treats the routine
 chown-permission warning as a failure (2026-09-14).** The archive share is
 never owned by the ssh user, so rsync's own `chown` step fails on *every*
@@ -230,6 +306,9 @@ every deletion because of it.
 | `scripts/gdl-cron.sh` | unattended wrapper: `stories` \| `profiles` \| `full-sweep` |
 | `scripts/systemd/` | the timers actually installed on the fetch host |
 | `scripts/test_gdl_sync.py` | its tests |
+| `scripts/check-session.py` | preflight: is there a usable Instagram `sessionid` in the Chrome cookie DB? (exit 1 = no) |
+| `scripts/stories-streak.py` | postflight: all stories sources empty for several days running? |
+| `scripts/test_session_guards.py` | tests for the two guards above (offline) |
 | `scripts/jd2-sync.ts` | JDownloader `.crawljob` generator, still used elsewhere |
 | `docs/gallery-dl.md` | the measurements behind every option in the fetcher — **read before changing pacing** |
 | `docs/jdownloader.md` | the older JD2 flow |
@@ -372,7 +451,11 @@ systemctl --user list-timers 'gdl-sync@*'
 
 Unit files are version-controlled in `scripts/systemd/` and installed to
 `~/.config/systemd/user/`. One templated service, `gdl-sync@.service`, takes
-the mode as its instance name and runs `gdl-cron.sh %i`.
+the mode as its instance name and runs `run-%i.sh` (the fixed-mode wrappers
+around `gdl-cron.sh` — they carry the Healthchecks URL; see "Healthchecks.io").
+Before 2026-10-14 it ran `gdl-cron.sh %i` directly, which skipped every ping.
+The profiles timer in the table is as originally installed; the repo's copy is
+weekly (see "2026-10-14" → "Open: profiles cadence").
 
 Three settings are load-bearing:
 
@@ -561,7 +644,12 @@ Two results are **not** failures, despite how they look:
 
 ### 2. Check the cookies before concluding you are blocked
 
-Free, and it separates a local fault from a server-side one:
+First, `~/gdl/check-session.py` — it reads the same cookie DB gdl does and says
+whether a `sessionid` exists and when it expires (never prints values). Do not
+trust the open browser tab to tell you: it keeps showing a logged-in page after
+the session has died; reload it.
+
+Then, free, and it separates a local fault from a server-side one:
 
 ```sh
 PATH=$HOME/.local/bin:$PATH gallery-dl \